Rough surfaced copy-sheet intermediate



July 12, 1966 J. L. REITTER 3,

ROUGH SURFACED COPY-SHEET INTERMEDIATE Filed NOV. 25, 1962 f/v va/vroz? JOHN L. Q5/7702 ATTOPA/EKS United States Patent 3,260,603 ROUGH SURFACED COPY-SHEET INTERMEDIATE John L. Reitter, St. Paul, Minn., assignor to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware Filed Nov. 23, 1962, Ser. No. 239,585 3 Claims. (Cl. 9687) This invention relates to the copying of graphic originals and is particularly applicable to the copying of smooth-surfaced originals such as photographic negatives or prints by a process involving reflex exposure of a transparent photosensitive film intermediate which is capable of reacting with an image-forming or copy sheet containing a silver soap when briefly heated in contact therewith.

Copying processes have recently been described in which as a first step a photosensitive film is exposed to actinic radiation while in contact with a graphic original having radiation-absorptive image areas and radiationrefleotive background areas. The photosensitive component, which normally is capable of reacting readily with silver soaps at moderately elevated temperature, is gradually converted to a non-reactive modification during irradiation. 'A differential conversion is effected at areas of the overlying coating corresponding to image and background areas of the original due to the differential reflectivity of those areas. Exposure is terminated as soon as the conversion is complete over the more reflective sections. The film is then placed in contact with an image or copy sheet carrying a silver soap, and the composite is heated. The unconverted photosensitive component at the image areas reacts with the silver soap, producing a copy corresponding to the graphic original.

The process is fully effective with graphic originals such as typewritten correspondence, pencil or pen-and-ink sketches, and printed pages of books, but has been found to be erratic and less effective when applied to photographic prints or negatives, slick-paper magazines, and similar originals.

The present invention overcomes these difiiculties and makes possible the consistently effective copying of all types of graphic originals by the process hereinabove described, by providing an improved photosensitive intermediate.

Surprisingly, it has now been ttound that simple embossing of the photosensitive film permits the copying of all classes of originals, including photographic prints and negatives, photost-at negatives and positives, printed films, books, pictures and various other forms of graphic representations and supporting surfaces.

Embossing is conveniently accomplished on the coated intermediate sheet material. The photosensitive coating is smoothly and uniformly aplied to the smooth surface of a transparent film or other supporting web which is then embossed in a fine pattern by any suitable method, providing a great number of tiny protrusions at the coated surface. The film may alternatively but less desirably be embossed prior to coating.

Other means for providing the desired protrusions at the coated surface will readily occur; for example, creped or crinkled paper or film provides a suitable surface where the crepe marks are sufl'lciently small, or the coated surface may be supplied with a disperse coating of scattered small beads or other particles, or a raised design may be applied to the surface by printing or by flocking or in other ways either before or after coating with the photosensitive material. In all instances the photosensitive surface is provided with a pattern of closely spaced protrusions having minimal contact area with a sheet or film held against the said surface and of very moderate height.

As an example, the protrusions may provide essentially 3,260,603 Patented July 12, 1966 pointed peaks at a height of at least about 1 /2 microns above the surrounding surface, the peaks being within at least about /8 inch lfrom each other and ordinarily much closer. Rounded or flat-topped protrusions are useful but show a tendency to cause undesirable skipping in the image areas of the resulting copy. Increased distance between protrusions may be permissible with films or sheet materials of increased rigidity but much closer spacing of point protrusions is desirable particularly on very thin and necesarily flimsy films and when copying intricate manuscripts requiring reproduction of small or narrow graphic markings. Protrusions of increased height are oridinarily less rugged but may be desirable Where the film intermediate is to be used in copying from softsurfaced graphic originals.

By way of further example, it has been found possible effectively to emboss a transparent photosensitive coated film intermediate sheet material by means of a simple process adapted for hand application with easily available equipment, whereby the utility of the invention has been well demonstrated. The process involves merely pressing a sheet of open-coat sandpaper against the reverse or uncoated surface of the photosensitive film supported on a yieldable surface. The resulting embossed film product under irradiation is selectively desensitized at the reflective areas of all types of graphic originals and, when appropriately further processed as hereinbefore indicated, yields copies of high quality; whereas the same coated but smooth-surfaced film under identical exposure and image development conditions is [found to remain reactive to silver soap over unpredictable large reflective areas of photostat positives and similar smooth-surfaced originals.

The procedures and materials employed will now be set forth in the form of a specific illustrative but nonlimiting example, in which all proportions are in parts by weight.

Example Thin (.001 inch) transparent tensilized polyethylene glycol terephthalate (Mylar) polyester film is uniformly and smoothly coated on one surface at a three mil coating orifice with a solution of 0.2 part by weight of 4-met-hoxyl-naphthol, 0.088 parts of erythrosin and 10 parts of ethyl cellulose in 90 parts of methyl ethyl ketone, and dried in the absence of actinic radiation, producing a reddish light-transmissive photosensitive film.

A portion of the coated film is laid on a pad of paper with the coated surface in contact with the paper. A sheet of sandpaper, more specifically grit 36 open coat aluminum oxide abrasive paper, is placed over the film with its grit surface against the uncoated film and is pressed against the film under a single slow pass of a 2-inch rubber-covered paperhangers roller applied with moderate hand pressure. The film is permanently roughened or embossed but not perforated.

White paper is coated with a continuous thin colorless layer of a composition prepared by mixing together in a ball mill 10 parts of silver behenate, one part of phthal-azinone, three parts of poly-tertiarybutylmcthacrylate and 86 parts of acetone, and the coating is dried.

The coated film is first placed with its coated surface in contact with a graphic original in the form of a glossy photostat positive print having a test pattern of black parallel lines of gradually increasing width on a white back-ground, and the original is exposed through the film to intense light from a bank of tungsten filament lamps. The exposure, which may take about 10 to 15 seconds, as determined for the particular light source employed, is sufficient to desensitize completely the sensitive coating above the reflective background areas of the original while only partially desensitizing the sensitive coating above the radiation-absorptive dark image areas.

The film is next placed with the coated surface in contact with the coated surface of the silver coated paper and the composite is heated, for example by pressing between flat platens at 110 C. for a few seconds. A copy of the original is produced on the silver-coated paper beneath the embossed areas of the film, with only very minor occurrence of white dots or skip marks as imperfections in the black image areas and with clean white background areas. Under the nonembosed areas of the film the silver-coated paper is badly blotched or irregularly darkened so that the test pattern is scarcely or not at all detectable.

The embossing step may be accomplished mechanically, for example by passing the film between a rubber backup roller and a steel pressure roller covered with a sleeve of abrasive paper, the coated surface of the film facing the rubber roller but preferably being protected from direct contact therewith by an intervening strip of paper. The two rollers are rotated at identical surface speeds. Pnessures of 30-40 lbs/sq. in. are typical, the requirements being sufi'icient pressure to produce the desired embossing effect without perforating the film. The procedure is schematically illustrated in FIGURE 1 of the accompanying drawing; FIGURE 2 similarly illustrates a portion of the film product in enlarged cross-section.

As illustrated, a sensitive intermediate sheet having a photosensitive coating 12 on a transparent film- 11 is placed between a rubber-covered roller 14 and a steel roller 15, the latter being covered with a sleeve of opencoat abrasive sheet material 16, the two rollers being pressed toward each other under constant tension. A protective thin paper web 19 may optionally be inserted between the roller 14 and the coated film 10. The film is embossed, by the abrasive particles, with closely spaced sharp protrusions 17, and in this case with corresponding depressions 18 at the opposite surface.

What is claimed is as follows:

1. A rough-surfaced photosensitive copy-sheet intermediate, capable of providing a differential pattern of reactivity with a silver soap image sheet reactive therewith, by exposing said intermediate to actinic radiation While in surface contact With a photographic original having differentially radiation-reflective image and background areas, said intermediate comprising a thin carrier web coated on one surface with a silver-soap-reactive composition capable olf being rendered nonreactive with a said si lver soap image sheet on exposure to said radiation, and having, extending over the coated surface, a pattern of spaced minute protrusions extending at least about 1%. microns above surrounding surface.

2. A roughasurfaced photosensitive copy-sheet intermediate capable, on being subjected to reflex exposure to actinic radiation while in surface contact with a smoothsurfaced original having differentially radiation-reflective image and background areas, of providing a corresponding differential pattern of reactivity for an image sheet containing a silver soap component, said intermediate comprising a thin transparent plastic film carrier web having on one surface a coating of a photosensitive composition normally rapidly visible reactive with a said image sheet at moderately elevated temperature and capable of being rendered non-reactive therewith on exposure to said radiation, and said plastic film being embossed over the copy area with a pattern of spaced minute peaked protrusions extending at least about 1% microns above the coated surface, the peaks of said protrusions being within at least about Vs inch of each other.

3. A rough-surfaced photosensitive copy-sheet intermediate comprising a thin transparent polyester plastic film carrier web having on one surface a thin reddish light-transmissive coating comprising 4 methoxy-1-naphthol, erythrosin, and a film-forming binder, said copysheet being embossed with a pattern of closely spaced minute peaked protrusions extending at least about 1% microns above the coated surface, the peaks of said protrusions being spaced not more than about /s inch apart.

References Cited by the Examiner UNITED STATES PATENTS 1,962,679 6/1934 Baker et al 9680 2,233,010 2/1941 Hipke et al. 96--67 X 2,286,834 6/ 1942 Rittenhouse '11734 2,295,632 9/1942 Buskes 96-47 2,381,704 8/ 1945 Terry 96--79 2,602,740 7/ 1952 Van Der Grinten 9647 2,795,522 6/1957 Johns 11734 2,815,307 9/1957 Beck 117-34 3,010,390 11/1961 Buskes 9628 X 3,010,391 11/ 1961 Buskes et a1 9628 X 3,091,528 5/1963 Buskes 9628 3,165,406 1/1965 Murray 117-34 FOREIGN PATENTS 226,614 10/ 1910 Germany.

NORMAN G. TORCHIN, Primary Examiner.

ALEXANDER D. RICCI, Examiner. R. L. STONE, c. BOWERS, Assistant Examiners. 

2. A ROUGH-SURFACED PHOTOSENSITIVE COPY-SHEET INTERMEDIATE CAPABLE, ON BEING SUBJECTED TO REFLEX EXPOSURE TO ACTINIC RADIATION WHILE IN SURFACE CONTACT WITH A SMOOTHSURFACED ORIGINAL HAVING DIFFERENTIALLY RADIATION-REFLECTIVE IMAGE AND BACKGROUND AREAS, OF PROVIDING A CORRESPONDING DIFFERENTIAL PATTERN OF REACTIVITY FOR AN IMAGE SHEET CONTAINING A SILVER SOAP COMPONENT, SAID INTERMEDIATE COMPRISING A THIN TRANSPARENT PLASTIC FILM CARRIER WEB HAVING ON ONE SURFACE A COATING OF A PHOTOSENEITIVE COMPOSITION NORMALLY RAPIDLY VISIBLE REACTIVE WITH A SAID IMAGE SHEET 